Allocate new buffer when parsing sensitive blob

.changes/next-release/bugfix-Parser-f872d831.json

@@ -0,0 +1,5 @@
+{
+  "type": "bugfix",
+  "category": "Parser",
+  "description": "Alloc new buffers from 0 offset when parsing the sensitive blob data and zero out the node shared buffer pool."
+}

lib/model/shape.js

@@ -354,7 +354,22 @@ function IntegerShape() {
 
 function BinaryShape() {
   Shape.apply(this, arguments);
-  this.toType = util.base64.decode;
+  this.toType = function(value) {
+    var buf = util.base64.decode(value);
+    if (this.isSensitive && util.isNode() && typeof util.Buffer.alloc === 'function') {
+  /* Node.js can create a Buffer that is not isolated.
+   * i.e. buf.byteLength !== buf.buffer.byteLength
+   * This means that the sensitive data is accessible to anyone with access to buf.buffer.
+   * If this is the node shared Buffer, then other code within this process _could_ find this secret.
+   * Copy sensitive data to an isolated Buffer and zero the sensitive data.
+   * While this is safe to do here, copying this code somewhere else may produce unexpected results.
+   */
+      var secureBuf = util.Buffer.alloc(buf.length, buf);
+      buf.fill(0);
+      buf = secureBuf;
+    }
+    return buf;
+  };
   this.toWireFormat = util.base64.encode;
 }